The Akkadians' nomadic origins have generally been assumed. However, the conventional prehistoric archaeological picture fails to illuminate those origins and the Akkadians' involvement in Akkad. Thus the origins of pastoral nomadism must be sought in the context of mixed farming within the Fertile Crescent, specifically during the PPNB. Subsequent expansion into marginal agricultural lands led to a symbiotic relationship between pastoral nomads and farmers. The Akkadians seem to have moved into the northern Arabian steppe and desert (Jezireh and Hamada) during the mid-seventh millennium B. C.; the PPNB/C populations apparently began intensive herding at the end of that period, and maintained ties to the Fertile Crescent seen in both exotic trade and everyday culture. They began to penetrate into Akkad during the time under discussion. Archaeological sequences in the Arabian desert suggest that the Akkadians probably were of a West Semitic (Levantine) background. Thus, the alluvium in the Akkadian area became a distinct entity as early as ca. 6000 B. C. and represented the early prehistoric forerunners to Akkadians of the fourth and third millennia B. C.